Simulation of Photovoltaic Panel Production as Complement to Ground Source Heat Pump System

This master thesis presents a new technological combination of two environmentally friendly sources of energy in order to provide DHW, and space heating. Solar energy is used for space heating, and DHW production using PV modules which supply direct current directly to electrical heating elements inside a water storage tank. On the other hand a GSHP system as another source of renewable energy provides heat in the water storage tank of the system in order to provide DHW and space heating. These two sources of renewable energy have been combined in this case-study in order to obtain a more efficient system, which will reduce the amount of electricity consumed by the GSHP system.The key aim of this study is to make simulations, and calculations of the amount ofelectrical energy that can be expected to be produced by a certain amount of PV modules that are already assembled on a house in Vantaa, southern Finland. This energy is then intended to be used as a complement to produce hot water in the heating system of the house beside the original GSHP system. Thus the amount of electrical energy purchased from the grid should be reduced and the compressor in the GSHP would need fewer starts which would reduce the heating cost of the GSHP system for space heating and providing hot water.The produced energy by the PV arrays in three different circuits will be charged directly to three electrical heating elements in the water storage tank of the existing system to satisfy the demand of the heating elements. The excess energy can be used to heat the water in the water storage tank to some extent which leads to a reduction of electricity consumption by the different components of the GSHP system.To increase the efficiency of the existing hybrid system, optimization of different PV configurations have been accomplished, and the results are compared. Optimization of the arrays in southern and western walls shows a DC power increase of 298 kWh/year compared with the existing PV configurations. Comparing the results from the optimization of the arrays on the western roof if the intention is to feed AC power to the components of the GSHP system shows a yearly AC power production of 1,646 kWh.This is with the consideration of no overproduction by the PV modules during the summer months. This means the optimized PV systems will be able to cover a larger part of summer demand compared with the existing system.

System Integration of PV/T Collectors in Solar Cooling Systems

The demand for cooling and air-conditioning of building is increasingly ever growing. This increase is mostly due to population and economic growth in developing countries, and also desire for a higher quality of thermal comfort. Increase in the use of conventional cooling systems results in larger carbon footprint and more greenhouse gases considering their higher electricity consumption, and it occasionally creates peaks in electricity demand from power supply grid. Solar energy as a renewable energy source is an alternative to drive the cooling machines since the cooling load is generally high when solar radiation is high. This thesis examines the performance of PV/T solar collector manufactured by Solarus company in a solar cooling system for an office building in Dubai, New Delhi, Los Angeles and Cape Town. The study is carried out by analyzing climate data and the requirements for thermal comfort in office buildings. Cooling systems strongly depend on weather conditions and local climate. Cooling load of buildings depend on many parameters such as ambient temperature, indoor comfort temperature, solar gain to the building and internal gains including; number of occupant and electrical devices. The simulations were carried out by selecting a suitable thermally driven chiller and modeling it with PV/T solar collector in Polysun software. Fractional primary energy saving and solar fraction were introduced as key figures of the project to evaluate the performance of cooling system. Several parametric studies and simulations were determined according to PV/T aperture area and hot water storage tank volume. The fractional primary energy saving analysis revealed that thermally driven chillers, particularly adsorption chillers are not suitable to be utilizing in small size of solar cooling systems in hot and tropic climates such as Dubai and New Delhi. Adsorption chillers require more thermal energy to meet the cooling load in hot and dry climates. The adsorption chillers operate in their full capacity and in higher coefficient of performance when they run in a moderate climate since they can properly reject the exhaust heat. The simulation results also indicated that PV/T solar collector have higher efficiency in warmer climates, however it requires a larger size of PV/T collectors to supply the thermally driven chillers for providing cooling in hot climates. Therefore using an electrical chiller as backup gives much better results in terms of primary energy savings, since PV/T electrical production also can be used for backup electrical chiller in a net metering mechanism.

Emissions from realistic operation of residential wood pellets heating systems

Emissions from residential combustion appliances vary significantly depending on the firing behaviours and combustion conditions, in addition to combustion technologies and fuel quality. Although wood pellet combustion in residential heating boilers is efficient, the combustion conditions during start-up and stop phases are not optimal and produce significantly high emissions such as carbon monoxide and hydrocarbon from incomplete combustion. The emissions from the start-up and stop phases of the pellet boilers are not fully taken into account in test methods for ecolabels which primarily focus on emissions during operation on full load and part load. The objective of the thesis is to investigate the emission characteristics during realistic operation of residential wood pellet boilers in order to identify when the major part of the annual emissions occur. Emissions from four residential wood pellet boilers were measured and characterized for three operating phases (start-up, steady and stop). Emissions from realistic operation of combined solar and wood pellet heating systems was continuously measured to investigate the influence of start-up and stop phases on total annual emissions. Measured emission data from the pellet devices were used to build an emission model to predict the annual emission factors from the dynamic operation of the heating system using the simulation software TRNSYS. Start-up emissions are found to vary with ignition type, supply of air and fuel, and time to complete the phase. Stop emissions are influenced by fan operation characteristics and the cleaning routine. Start-up and stop phases under realistic operation conditions contribute 80 – 95% of annual carbon monoxide (CO) emission, 60 – 90% total hydrocarbon (TOC), 10 – 20% of nitrogen oxides (NO), and 30 – 40% particles emissions. Annual emission factors from realistic operation of tested residential heating system with a top fed wood pelt boiler can be between 190 and 400 mg/MJ for the CO emissions, between 60 and 95 mg/MJ for the NO, between 6 and 25 mg/MJ for the TOC, between 30 and 116 mg/MJ for the particulate matter and between 2x10-13 /MJ and 4x10-13 /MJ for the number of particles. If the boiler has the cleaning sequence with compressed air such as in boiler B2, annual CO emission factor can be up to 550 mg/MJ. Average CO, TOC and particles emissions under realistic annual condition were greater than the limits values of two eco labels. These results highlight the importance of start-up and stop phases in annual emission factors (especially CO and TOC). Since a large or dominating part of the annual emissions in real operation arise from the start-up and stop sequences, test methods required by the ecolabels should take these emissions into account. In this way it will encourage the boiler manufacturers to minimize annual emissions. The annual emissions of residential pellet heating system can be reduced by optimizing the number of start-ups of the pellet boiler. It is possible to reduce up to 85% of the number of start-ups by optimizing the system design and its controller such as switching of the boiler pump after it stops, using two temperature sensors for boiler ON/OFF control, optimizing of the positions of the connections to the storage tank, increasing the mixing valve temperature in the boiler circuit and decreasing the pump flow rate. For 85 % reduction of start-ups, 75 % of CO and TOC emission factors were reduced while 13% increase in NO and 15 % increase in particle emissions was observed.

Identifiering av parametrar till ackumulatortanken Solus1050 från consolar - en metodbeskrivning

This report describes the work done creating a computer model of a kombi tank from Consolar. The model was created with Presim/Trnsys and Fittrn and DF were used to identify the parameters. Measurements were carried out and were used to identify the values of the parameters in the model. The identifications were first done for every circuit separately. After that, all parameters are normally identified together using all the measurements. Finally the model should be compared with other measurements, preferable realistic ones. The two last steps have not yet been carried out, because of problems finding a good model for the domestic hot water circuit.The model of the domestic hot water circuit give relatively good results for low flows at 5 l/min, but is not good for higher flows. In the report suggestions for improving the model are given. However, there was not enough time to test this within the project as much time was spent trying to solve problems with the model crashing. Suggestions for improving the model for the domestic circuit are given in chapter 4.4. The improved equations that are to be used in the improved model are given by equation 4.18, 4.19 and 4.22.Also for the boiler circuit and the solar circuit there are improvements that can be done. The model presented here has a few shortcomings, but with some extra work, an improved model can be created. In the attachment (Bilaga 1) is a description of the used model and all the identified parameters.A qualitative assessment of the store was also performed based on the measurements and the modelling carried out. The following summary of this can be given: Hot Water PreparationThe principle for controlling the flow on the primary side seems to work well in order to achieve good stratification. Temperatures in the bottom of the store after a short use of hot water, at a coldwater temperature of 12°C, was around 28-30°C. This was almost independent of the temperature in the store and the DHW-flow.The measured UA-values of the heat exchangers are not very reliable, but indicates that the heat transfer rates are much better than for the Conus 500, and in the same range as for other stores tested at SERC.The function of the mixing valve is not perfect (see diagram 4.3, where Tout1 is the outlet hot water temperature, and Tdhwo and Tdhw1 is the inlet temperature to the hot and cold side of the valve respectively). The outlet temperature varies a lot with different temperatures in the storage and is going down from 61°C to 47°C before the cold port is fully closed. This gives a problem to find a suitable temperature setting and gives also a risk that the auxiliary heating is increased instead of the set temperature of the valve, when the hot water temperature is to low.Collector circuitThe UA-value of the collector heat exchanger is much higher than the value for Conus 500, and in the same range as the heat exchangers in other stores tested at SERC.Boiler circuitThe valve in the boiler circuit is used to supply water from the boiler at two different heights, depending on the temperature of the water. At temperatures from the boiler above 58.2°C, all the water is injected to the upper inlet. At temperatures below 53.9°C all the water is injected to the lower inlet. At 56°C the water flow is equally divided between the two inlets. Detailed studies of the behaviour at the upper inlet shows that better accuracy of the model would have been achieved using three double ports in the model instead of two. The shape of the upper inlet makes turbulence, that could be modelled using two different inlets. Heat lossesThe heat losses per m3 are much smaller for the Solus 1050, than for the Conus 500 Storage. However, they are higher than those for some good stores tested at SERC. The pipes that are penetrating the insulation give air leakage and cold bridges, which could be a major part of the losses from the storage. The identified losses from the bottom of the storage are exceptionally high, but have less importance for the heat losses, due to the lower temperatures in the bottom. High losses from the bottom can be caused by air leakage through the insulation at the pipe connections of the storage.

Webbplats och grafisk profil för Falu Tank AB : samt teoretisk fördjupning inom webbdesign

I detta examensarbete har en webbplats skapats för Falu Tank AB med hjälp av Jennifer Flemings utvecklingsmodell, även framtagning av en logotyp och grafisk profil med tillhörande manual har ingått i examensarbetet. Falu Tank AB utför nytillverkning, rekonditionering samt kontroll av petroleumtankar. De erbjuder också oljeavskiljare, pumpöar och dubbelmantlade tankar. Arbetet har bestått av en bakgrundsundersökning på Falu Tank AB, samt litteraturstudier i webbdesign och grafisk profilering, med en teoretisk fördjupning inom webbdesign. Bra webbdesign innebär i första hand att sidan är välstrukturerad, enhetlig, lättnavigerad, användarvänlig och att den har en bra harmoni. Målet med webbplatsen var att den skulle vara funktionell, proffsig, och modern, med en passande design för att attrahera fler besökare. Jennifer Flemings utvecklingsmodell lämpade sig mycket väl vid utformningen av webbplatsen. Falu Tanks logotyp kändes gammal och intetsägande dessutom saknades en grafisk profil. Den framtagna profilen innefattar logotyp, färg och typografi, men även formgivning av visitkort, brevpapper och fakturor. Målet med den grafiska profilen var ett ge Falu Tank ett enhetligt, modernt och stilrent intryck inför kommande marknadsföring. Resultatet blev en stilren och tydlig grafisk profil med stark koppling till Falu Tank. (PDF1 - Rapport) (PDF2 - Bilagor) (PDF3 - Grafisk Manual)

Energy Storage for a Grid-Connected PV-System: A Feasibility Study

The work presented in this thesis concerns the dimensioning of an Energy Storage System (ESS) which will be used as an energy buffer for a grid-connected PV plant. This ESS should help managing the PV plant to inject electricity into the grid according to the requirements of the grid System Operator. It is desired to obtain a final production not below 1300kWh/kWp with a maximum ESS budget of 0.9€/Wp. The PV plant will be sited in Martinique Island and connected to the main grid. This grid is a small one where the perturbations due clouds in the PV generation are not negligible anymore. A software simulation tool, incorporating a model for the PV-plant production, the ESS and the required injection pattern of electricity into the grid has been developed in MS Excel. This tool has been used to optimize the relevant parameters defining the ESS so that the feed-in of electricity into the grid can be controlled to fulfill the conditions given by the System Operator. The inputs used for this simulation tool are, besides the conditions given by the System Operator on the allowed injection pattern, the production data from a similar PV-plant in a close-by location, and variables for defining the ESS. The PV production data used is from a site with similar climate and weather conditions as for the site on the Martinique Island and hence gives information on the short term insolation variations as well as expected annual electricity production. The ESS capacity and the injected electric energy will be the main figures to compare while doing an economic study of the whole plant. Hence, the Net Present Value, Benefit to Cost method and Pay-back period studies are carried on as dependent of the ESS capacity. The conclusion of this work is that it is possible to obtain the requested injection pattern by using an ESS. The design of the ESS can be made within an acceptable budget. The capacity of ESS to link with the PV system depends on the priorities of the final output characteristics, and it also depends on which economic parameter that is chosen as a priority.

Energy Efficiency through Thermal Energy Storage : Possibilities for the Swedish Building Stock

The need for heating and cooling in buildings constitutes a considerable part of the total energy use in a country and reducing this need is of outmost importance in order to reach national and international goals for reducing energy use and emissions. One important way of reaching these goals is to increase the proportion of renewable energy used for heating and cooling of buildings. Perhaps the largest obstacle with this is the often occurring mismatch between the availability of renewable energy and the need for heating or cooling, hindering this energy to be used directly. This is one of the problems that can be solved by using thermal energy storage (TES) in order to save the heat or cold from when it is available to when it is needed. This thesis is focusing on the combination of TES techniques and buildings to achieve increased energy efficiency for heating and cooling. Various techniques used for TES as well as the combination of TES in buildings have been investigated and summarized through an extensive literature review. A survey of the Swedish building stock was also performed in order to define building types common in Sweden. Within the scope of this thesis, the survey resulted in the selection of three building types, two single family houses and one office building, out of which the two residential buildings were used in a simulation case study of passive TES with increased thermal mass (both sensible and latent). The second case study presented in the thesis is an evaluation of an existing seasonal borehole storage of solar heat for a residential community. In this case, real measurement data was used in the evaluation and in comparisons with earlier evaluations. The literature reviews showed that using TES opens up potential for reduced energy demand and reduced peak heating and cooling loads as well as possibilities for an increased share of renewable energy to cover the energy demand. By using passive storage through increased thermal mass of a building it is also possible to reduce variations in the indoor temperature and especially reduce excess temperatures during warm periods, which could result in avoiding active cooling in a building that would otherwise need it. The analysis of the combination of TES and building types confirmed that TES has a significant potential for increased energy efficiency in buildings but also highlighted the fact that there is still much research required before some of the technologies can become commercially available. In the simulation case study it was concluded that only a small reduction in heating demand is possible with increased thermal mass, but that the time with indoor temperatures above 24 °C can be reduced by up to 20%. The case study of the borehole storage system showed that although the storage system worked as planned, heat losses in the rest of the system as well as some problems with the system operation resulted in a lower solar fraction than projected. The work presented within this thesis has shown that TES is already used successfully for many building applications (e.g. domestic hot water stores and water tanks for storing solar heat) but that there still is much potential in further use of TES. There are, however, barriers such as a need for more research for some storage technologies as well as storage materials, especially phase change material storage and thermochemical storage.

Thermal energy storage in Swedish single family houses : a case study

In a Nordic climate, space heating (SH) and domestic hot water (DHW) used in buildings constitute a considerable part of the total energy use in the country. For 2010, energy used for SH and DHW amounted to almost 90 TWh in Sweden which corresponds to 60 % of the energy used in the residential and service sector, or almost 24 % of the total final energy use for the country. Storing heat and cold with the use of thermal energy storage (TES) can be one way of increasing the energy efficiency of a building by opening up possibilities for alternative sources of heat or cold through a reduced mismatch between supply and demand. Thermal energy storage without the use of specific control systems are said to be passive and different applications using passive TES have been shown to increase energy efficiency and/or reduce power peaks of systems supplying the heating and cooling needs of buildings, as well as having an effect on the indoor climate. Results are however not consistent between studies and focus tend to be on the reduction of cooling energy or cooling power peaks. In this paper, passive TES introduced through an increased thermal mass in the building envelope to two single family houses with different insulation standard is investigated with building energy simulations. A Nordic climate is used and the focus of this study is both on the reduction of space heating demand and space heating power, as well as on reduction of excess temperatures in residential single family houses without active cooling systems. Care is taken to keep the building envelope characteristics other than the thermal mass equal for all cases so that any observations made can be derived to the change in thermal mass. Results show that increasing the sensible thermal mass in a single family house can reduce the heating demand only slightly (1-4 %) and reduce excess temperatures (temperatures above 24 degrees C) by up to 20 %. Adding a layer of PCM (phase change materials) to the light building construction can give similar reduction in heating demand and excess temperatures, however the phase change temperature is important for the results.

Energy Efficiency through Thermal Energy Storage - Evaluation of the Possibilities for the Swedish Building Stock, Phase 1

As a first step in assessing the potential of thermal energy storage in Swedish buildings, the current situation of the Swedish building stock and different storage methods are discussed in this paper. Overall, many buildings are from the 1960’s or earlier having a relatively high energy demand, creating opportunities for large energy savings. The major means of heating are electricity for detached houses and district heating for multi dwelling houses and premises. Cooling needs are relatively low but steadily increasing, emphasizing the need to consider energy storage for both heat and cold. The thermal mass of a building is important for passive storage of thermal energy but this has not been considered much when constructing buildings in Sweden. Instead, common ways of storing thermal energy in Swedish buildings today is in water storage tanks or in the ground using boreholes, while latent thermal energy storage is still very uncommon.

Evaluation of a high temperature solar thermal seasonal borehole storage

A solar thermal system with seasonal borehole storage for heating of a residential area in Anneberg, Sweden, approximately 10 km north of Stockholm, has been in operation since late 2002. Originally, the project was part of the EU THERMIE project “Large-scale Solar Heating Systems for Housing Developments” (REB/0061/97) and was the first solar heating plant in Europe with borehole storage in rock not utilizing a heat pump. Earlier evaluations of the system show lower performance than the preliminary simulation study, with residents complaining of a high use of electricity for domestic hot water (DHW) preparation and auxiliary heating. One explanation mentioned in the earlier evaluations is that the borehole storage had not yet reached “steady state” temperatures at the time of evaluation. Many years have passed since then and this paper presents results from a new evaluation. The main aim of this work is to evaluate the current performance of the system based on several key figures, as well as on system function based on available measurement data. The analysis show that though the borehole storage now has reached a quasi-steady state and operates as intended, the auxiliary electricity consumption is much higher than the original design values largely due to high losses in the distribution network, higher heat loads as well as lower solar gains.

Economic Evaluation of a Solar Charged Thermal Energy Store for Space Heating

A thermal energy store corrects the misalignment of heating demand in the winter relative to solar thermal energy gathered in the summer. This thesis reviews the viability of a solar charged hot water tank thermal energy store for a school at latitude 56.25N, longitude -120.85W

Thomas-Fermi ground state of dipolar fermions in a circular storage ring

Recent developments in the field of ultracold gases has led to the production of degenerate samples of polar molecules. These have large static electric-dipole moments, which in turn causes the molecules to interact strongly. We investigate the interaction of polar particles in waveguide geometries subject to an applied polarizing field. For circular waveguides, tilting the direction of the polarizing field creates a periodic inhomogeneity of the interparticle interaction. We explore the consequences of geometry and interaction for stability of the ground state within the Thomas-Fermi model. Certain combinations of tilt angles and interaction strengths are found to preclude the existence of a stable Thomas-Fermi ground state. The system is shown to exhibit different behavior for quasi-one-dimensional and three-dimensional trapping geometries.